I remember doing a lot of fiddling when I first got my PW. I started out with 17 during the day. Since then I have gone down and down.
Now I just put it at 4 or 5 and leave it there. If I read in the bedroom with a side lamp, I go down to 3. I never read in complete darkness. I could probable go to 2 if I did that.
This gives me a kindle that is just a tad brighter in the backround than my K3 and I can go all day in any light situation and not have to fiddle with it anymore.
3 darkish room